Phase Evolution and Mechanical Properties of Suction Cast Ti-Fe-Co Ternary Alloys

The current work has been undertaken with an aim to investigate the phase evolution and mechanical behaviour of Ti-Fe-Co ternary alloys. Extensive electron microscopic studies have been carried out to identify the phases present in the microstructure of the suction cast Ti-Fe-Co ternary alloys. The SEM micrographs of the investigated Ti-Fe-Co alloys reveal that the microstructures consist of eutectic matrix (L -> (beta-Ti)(ss) + Ti(Fe,Co) and/or L ->(beta-Ti)(ss) + Ti-2(Co,Fe)) along with different dendritic phases ((beta-Ti)(ss) or Ti(Fe,Co), Ti-2(Co,Fe)) depending on concentration of Co. Ti70Fe20Co10 and Ti75Fe15Co10 alloys show the bimodal eutectics, ((beta-Ti)(ss) + Ti(Fe,Co)) and ((beta-Ti)(ss) + Ti-2(Co,Fe)). The room temperature uniaxial compressive test of the Ti70Fe20Co10 ternary alloy exhibits simultaneous improvement in compressive strength (similar to 2819 MPa) and plasticity (similar to 8.5%) among the series of investigated Ti-Fe-Co ternary alloys. Fractography of the surface of Ti70Fe20Co10 ternary alloy reveals mixed mode of fracture. The significant outcome of the investigated Ti-Fe-Co alloys is that, the plasticity of the alloys can be improved by the development of bimodal eutectics in the microstructure or by incorporating disordered dendritic phase.